1. Field of the Invention
The present invention relates in general to cooling the core engine area of a turbojet propulsion system and relates particularly to the use of waste air from a laminar flow nacelle system as a source of engine core compartment cooling air.
2. Description of Prior Developments
Conventional turbojet propulsion systems include a core compartment cooling system which bleeds cooling air from the air cycle of the propulsion system. This cooling air is extracted through a variable bypass valve and directed to a manifold which distributes the air around the engine core compartment. Because this cooling air bypasses the core engine and escapes combustion, it detracts from the efficiency and performance of the propulsion system.
A system previously unrelated to the core compartment cooling system is known as a laminar flow nacelle system. This system improves the performance of turbojet engines by reducing drag around the fan cowl and engine nacelle by drawing air into the cowl from points along its outer surface. A pump is used to draw the air into the cowl and to exhaust the air into the engine fan compartment where it flows to atmosphere through a fan cowl vent port. The energy of the exhausted air is lost once the air enters the atmosphere. It would be advantageous to use this exhausted air for some additional engine function rather than to simply exhaust it to atmosphere.
Accordingly, a need exists for increasing the efficiency of a turbojet core engine compartment cooling system and for applying the exhaust air from a laminar flow nacelle system to some useful purpose.